Posted
by
Zonk
on Friday June 17, 2005 @08:18PM
from the i'm-my-own-grandpa dept.

goldfishy writes "If you went back in time and met your teenage parents, you could not split them up and prevent your birth - even if you wanted to, a new quantum model has stated. Researchers speculate that time travel can occur within a kind of feedback loop where backwards movement is possible, but only in a way that is 'complementary' to the present. In theory, you could go back in time and meet your infant father but you could not kill him." From the article: "Quantum behaviour is governed by probabilities. Before something has actually been observed, there are a number of possibilities regarding its state. But once its state has been measured those possibilities shrink to one - uncertainty is eliminated."

Many, many years ago when I was 23I was married to a Wider who was purty as can beThis Wider had a grown-up daughter who had hair of redMy father fell in love with her and soon they two were wed

This made my dad my son-in-law and changed my very lifeFor my daughter was my mother cause she was my father's wifeTo complicate the matter even though it brought me joyI soon became the father of a bouncing baby boy

I'm my own grampa,I'm my own grampaIt sounds funny I knowBut it really is soI'm my own grampa

My little baby then became a brother-in-law to dadAnd so became my uncle though it made me very sadFor if he was my uncle then that also made him brotherOf the Wider's grown up daughter who of course was my step-mother

My father's wife then had a son who kept them on the runAnd he became my granchild for he was my daughters sonMy wife is now my mother's mother and it makes me blueBecause although she is my wife she's my grandmother too

I'm my own grampa,I'm my own grampaIt sounds funny I knowBut it really is soI'm my own grampa

Oh if my wife is my grandmother then I'm her grandchildAnd every time I think of it, it nearly drives me wildFor now I have become strangest case you ever sawAs husband of my own grandmother I'm my own grampa

I'm my own grampa,I'm my own grampaIt sounds funny I knowBut it really is soI'm my own grampa

You're thinking of "--All You Zombies--". "By His Bootstraps" is a similarly structured story about a man who is visited by future versions of himself, who give him advice. It is also a closed time loop, but I think the one in "All You Zombies" is considerably more convoluted.

The circumstances of the protagonist's conception and birth are an elaborate setup which can exist only because of the interference of the protagonist as an older man in his own past - he is his own mother and father, and in variou

Then you should read "Up the Line" by Robert Silverberg. That's exactly the subject matter -- guy goes back in time and does a maternal ancestor. Repeatedly and in a manner you'll probably sympathize with. Quite entertaining and very, very well done as you would expect of Silverberg.

Hereforth, I propose that all mass in our universe is comprised of elaborate boolean operations on chicken. After all, it is a well-known truth that chicken tastes like everything, and it also helps explain why so much of DNA is the same throughout species.

Unfortunately, I don't have a concise mathematical model to support this hypothesis yet, but I'm sure there's someone resourceful out there who can take care of all that hand-waving stuff.

It tries to use the fact that we observe no disappearing people, or other strange temporal modifications as an argument that such things don't happen, and are thus impossible. But if somebody actually changed the way a wave function collapsed at some time in the past, why on earth would we expect to remember things from the way it was "before" it had been changed, since the change by definition happened in our own past, and thus to us it always occurred the way it now occurs? This isn't a logical argument. And it explains part of the aesthetic appeal of the many-worlds interpretation.

In pure quantum mechanics, time is a special property because wave function collapse via quantum operators (i.e. "observation") is a privileged thing that moves in only one direction. In general relativity, time doesn't have a privileged status. I don't see how you are going to reconcile that basic difference without coming up with a more complete theory (i.e. quantum gravity, GUT, etc.), but then again, my undergrad physics major knowledge is a bit rusty five years later.

> It tries to use the fact that we observe no disappearing people, or other strange temporal modifications as an argument that such things don't happen, and are thus impossible.

IIRC it has been proven that no time machine could take you back before the time when the machine was created, so unless someone has already created on and kept it secret we shouldn't be seeing tamper effects or visitors from the future anyway.

Nobody has ever proved that. What happens is that everybody accepts this fact as a base, and build physics from there. If you assume that a consequence can never happen before the cause, you end up with a model where is impossible to build a time machine that goes to the past.

The reason I've always understood is that the only theoretical model for (backward) time travel thus far involves temporally dialating (which is in itself, forward time manipulation) one end of a wormhole by sending it around a big circle at near-c. You then step back through the wormhole, back in time across the temporally dialated wormhole, and come out... a few feet away, where you then walk over to the same end you walked through last time and step back across time again. But at some point the point in time you step back across will be when the other end of the wormhole is still on it's journey through space and thus you CAN'T just walk over to the stationary end and do it again. Thus, you can never travel back before the time machine was built, because there needs to be the temporally dialated wormholes (the time machine) to come out of. It's not temporal teleportation.

Of course, even that model may be incorrect [slashdot.org], and timetravel may be utterly impossible (unless by some other strange means).

Personally, after that thread I just linked, I'm leaning in favor of impossible. If it were possible though, I definitely go with the many-worlds interpretation. (Hell, I already go with the many-worlds intrepretation just of quantum physics. Wave collapse my ass).

IIRC it has been proven that no time machine could take you back before the time when the machine was created, so unless someone has already created on and kept it secret we shouldn't be seeing tamper effects or visitors from the future anyway.

1. Never use the word "proven" around scientists. They'll kick your butt for it.

2. The theory of which you refer to is only applicable to using stable wormholes for time travel.

3. Stable wormholes are a thought experiment and have not been shown to exist. (In fact

There's evidence of time travel all around you, you're just not paying attention to it. Much of the inexplicable in the world is due to time travel. A type of time travel is responsible for the creation and re-creation of the universe itself.

In pure quantum mechanics, time is a special property because wave function collapse via quantum operators (i.e. "observation") is a privileged thing that moves in only one direction. In general relativity, time doesn't have a privileged status.

In nonrelativistic QM you mean. In the Dirac and Klein-Gordon equations, time is treated identically with the other dimensions, ie, the Dirac and Klein-Gordon equations are Lorentz invariant. So, yes, time-reversal is something that must be dealt with in relativistic QM. Unfortunately, these equations only describe a few very restricted situations, so they are not as generally applicable as the Schroedinger equation. Also, they only include special relativity, not general relativity, which seems to be where the time-travel is coming from in the as you said frustratingly vague article.

More bad science in the article:

Quantum behaviour is governed by probabilities. Before something has actually been observed, there are a number of possibilities regarding its state. But once its state has been measured those possibilities shrink to one - uncertainty is eliminated.

This is a common misconception. Prior to an observation, any system has a perfectly well defined state: its wave-function. This state, however, may or may not determine various properties of the system. In fact, for a given wave-function, or state, most properties (ie position, velocity, kinetic energy, etc) are restricted to a certain set of eigenvalues, and the wave-function merely determines the probability that a measurement of that property will yield any particular eigenvalue. Immediately after the measurement, the system will be in a state such that that particular property is exactly determined (ie the wave-function will have changed so that the probability of measuring that value for that property is 1, and the probability of measuring any other eigenvalue for that property is 0). This is called the collapse of the wave-function. However, other properties, some of which may have been uniquely determined by the previous wave-function, some of which were not, are now not uniquely determined.

In other words, what the article said was precisely wrong. Any system always has exactly one state which it is in, and after a measurement (or observation), whatever was measured is no longer uncertain, but most other properties are still uncertain.

IANA Physicist, yet. I have just finished my junior level undergrad physics courses, and am currently working for the summer at the Fermi National Accelerator Laboratory. Just to establish credentials.

My point is: "observation" is a meaningless concept. All points in the universe continuously "observe" all other points in the universe. Nothing is *ever* in an "unobserved" state, except perhaps for a duration shorter than plank time.

You speak of "if I measured the position of an electron, then at the moment I measured it..." but that's nonsense, really. The position of an electron is continuously measured, as is its momentum, by the space around it. Nothing can ever be unobserved.

The physicist David Deutsch had a theory that McFly could kill his own father, but that this would just spawn off a new time line in which his father died young and didn't have a kid, in parallel with the time line in which there was no murder and McFly was born. So you could go back and time and do whatever you want, but it would not affect your own history.

It all falls out of the many-worlds interpretation of quantum mechanics; the closed time-like loops would not "really" be closed and paradoxes could not happen, but you could meet many copies of yourself. Or find out what might have happened had you made a different decision.

Exactly, theorizing about time travel is about as scientific as "Intelligent Design."

Stephen Hawking has an ongoing bet regarding the so-called Chronology Protection Hypothesis, i.e. that the laws of nature conspire to prevent time travel on a macroscopic scale. Just because it leads to some problems that our brains find difficult to comprehend doesn't mean it's somehow unscientific.

In other words, even if you take a trip back in time with the specific intention of killing your father, so long as you know he is happily sitting in his chair when you leave him in the present, you can be sure that something will prevent you from murdering him in the past

This means that you cannot be killed when you go back in time, nor can you kill or destroy anything! That's just perfect!!

Go back in time and be able to observe, only... no ability to interact with anyone either... it should be kinda like ghosts... we go back in time and observe and be like ghosts in the sense that we cannot interact and change anything that has already happened but only observe!

Imagine the possibilities of history classes of the future... maybe there are already a lot of ghosts watching us right now... the future students studying history!!

From the summary of the film, I gather that this is the film adaptation of Vintage Season by Lawrence O'Donnell... an excellent story. I read it in Science Fiction Hall of Fame Volume 2A ed. Ben Bova.
The point is that even though these time travellers could possibly change the events that they are witnessing, they are forbidden by the rules in the future where they come from because changing anything could potentially wipe out the future. Seeing how one of the characters (a woman who is not fond of follow

Actually, there's nothing that would prevent you from being killed on your journey to the past. You just couldn't kill your past self.
Your present future is unknown, so you may not survive your trip to the past.

Here's an interesting twist: I can change the past in a way that changes the future, if I do so in a way that I don't know now. I could, for example, buy some shares of a stock that I know will rise a hundred-fold in value, but make sure that I don't get the money until after the moment I depart current time. Since I don't know that I don't have an envelope worth millions of dollars hidden, with a mechanism that will inform me of it, say, a week after my time-travel tip, it does not contradict what is known about the present that I become a millionaire a week from now.

"Clearly, the present never is changed by mischievous time-travellers: people don't suddenly fade into the ether because a rerun of events has prevented their births - that much is obvious."

That's not clear at all. If I went back in time and killed the baby George W Bush, it's like he would disappear in the middle of a speech. Rather the entire course of history branching from that moment would be changed, so that in the "present" no one would ever know GW had existed.

Would the people in the present suddenly vacuum to a moment where George Dubya is gone?

Your explanation does not make any more sense than what you quoted.

If you were to travel back in time two years, and were to murder my dog that I was walking at the time, what would happen? Would the leash just go empty, and or would I teleport back to a time before I knew the dog?

Basically, if time travel is actually possible, the instant that you travel back in time, you would create a fork in the past; you go back to 1978, and every single event prior to the time that you land in may be the same, but as soon as you land in 1978 you create a version of 1978 where you existed. Getting back to your own future would be really difficult, if not impossible.

The cool thing is, if you kill someone, in that timeline that person completely ce

The problem with this, of course, is that it only affects *that* timeline and any future forks created from that point onwards; it doesn't change the fact that back here, in our timeline, W became the president and launched another Gulf War.

I am sick of this democrat-republican warring permeating every aspect of society. Can't we become suspicious at other countries and invade them together, as Americans?

Couldn't you go back in time to kill your grandfather, only to have him rematerialize out of quantum randomness 5 minutes later? It's not impossible, just really improbable... maybe that's the protection mechanism.

> Couldn't you go back in time to kill your grandfather, only to have him rematerialize out of quantum randomness 5 minutes later? It's not impossible, just really improbable... maybe that's the protection mechanism.

The actual protection mechanism is that you discover your grandfather to still be a young stud rather than a cranky old man, and he gives you a good ass-beating before sending you back where you belong.

Lets say that at t = 0 your father is alive. And you go back to t = -10 to kill him. Let's say, further, that you kill him. So at t = -10 your father is dead. Then at t = 0 your dad is dead. This is a contradiction by hypothesis. The logic here is valid, so some premise must fail.

So it is logically impossible to kill your own father, given a relatively naive understanding of causation and fatherhood. A more nuanced understanding of causation and space-time might include things like "branching universes" and the like. Which is perfectly fine. But then there's the philoshical issue whether the person killed is actually your father or "merely" your "parallel universe father."

Lets say that at t = 0 your father is alive. And you go back to t = -10 to kill him. Let's say, further, that you kill him. So at t = -10 your father is dead. Then at t = 0 your dad is dead. This is a contradiction by hypothesis. The logic here is valid, so some premise must fail.

There are numerous problems with your "proof". Here are some assumptions that you gloss over:

- You assume that t automatically progresses from -10 to 0, with all other values in tact. That is, you assume that if father is d

"You go back to kill your father, but you'd arrive after he'd left the room, you wouldn't find him, or you'd change your mind," said Professor Greenberger.

Anyone else having difficulty imagining a scenario where it would be "impossible" to kill somebody?

I mean sure, there could be the above difficulties - but short of a divine miracle, what could possibly stop (for example) a determined psychopath from doing everything possible to kill his own father?

He goes back in time, goes to stab his Father with a knife - and then what? The knife just disappears? The boring scenarios listed in the article could only save the father's life for so long if the guy was a true Psycho, and really determined.

If I went back in time, and killed my mum, I wouldn't have been born to go back in time to kill my mum?So she wouldn't have died, leaving her to eventually give birth to me, for me to go back in time and kill her, preventing her from getting pregnant with me, meaning I would never have existed to go back and kill her?

I'm quite sure someone like Hawking will soon step in and say that though time travel of something is theoretically possible, that no intelligent being would be able to make the trip successfully because no information would be able to travel back in time.

The one thing that always bothered me about those time travel movies (besides the ridiculous timetravel part) like "Back To the Future", is that you wouldn't have to go to extremes to prevent your birth. All you would have to do is bump into your Mom or Dad to delay them for 1 second; that slight change in the timeline would guarantee that it would be a different sperm that won the race to impregnate your mom.

"Before something has actually been observed, there are a number of possibilities regarding its state. But once its state has been measured those possibilities shrink to one - uncertainty is eliminated."

There must be more here than it sounds, as this sounds like "once something has occurred, it has occurred, not something else." Well, duh. I didn't know that.
But it really proves nothing. I mean, if you go back in time and kill your grandparents, then you would never have observed their existence, so

Basically all this article is saying is that all time travel must consist of closed timelike loops. That is, you "fulfill" the present, rather than altering it. This isn't news - it's the only kind of timelike loop that can exist in GR anyway. The difference here is that quantum mechanics also forces them to be the only ones that exist.

Point of note, however: as far as I know, we don't actually have the math to deal with the formation of a topological change in a surface (i.e., the "alteration" of a timeline). This is very much akin to a wave crashing - fluid dynamics works up until the exact point when the top of the wave touches the rest of the ocean. After that point, the math breaks down. So it's a little difficult to say "X isn't possible, because the math won't allow it" when theorists are in fact only using math that won't allow it. So it's moderately circular. That's GR. In QM, we don't actually have the math that deals with the collapse of the wavefunction (the 'measurement'), and so again, it's moderately circular. If you instead suppose that the wavefunction doesn't actually collapse, then of course you can change the past - you just end up following a different course in probability the second time around.

Examples of closed timelike loops actually are more common than you think in modern scifi/fantasy. Harry Potter and the Prisoner of Azkaban had an excellent example of a CTL, and the timetravel used in Anne McCaffrey's Pern series are entirely CTLs. This leads to statements like "I know I can do this, because I've done it already."

The problem with CTLs is that they muck with certain people's belief in free will.

If, for example, you knew a picture would be taken, you could reflect light from your body and appear in that picture, thereby altering the future.

Assuming you didn't exist in the picture before you went back in time.

And it just moves up from there for all other physical effects. Nothing touched, no air breathed, no light disturbed, nothing.

Unless it was already disturbed to begin with.

Again, there's no real logical problem here. Just the fact that you would have to disassociate yourself from the fact that all of your future actions are possible.

I don't necessarily agree with time travel. A closed timelike loop is essentially the equivalent of a monkey popping out of thin air, and then disappearing a few seconds later. It seems idiotic, and completely counter to all natural laws. But that wouldn't be the first time nature did that to us.

Nah... it gets better than that. Unlike what we see in Doctor Who and such, time travel would be a VERY dangerous thing.

For example... if you try to assasinate your mother before you are conceived then since time is self consistent something will prevent you. That is what this theory is saying. Since you have observed the state everything in known in that state will be self consistent.

So... since we know that we can't change any part of the past that we know lets create a scenario.

In quantum physics, observing is altering. Thus, the question is between the many-worlds or the self-consistency theories.

In the many-worlds theory, if you alter the past a new timeline is created, with your changes in place. If you kill your mother, then the other you doesn't exist, but since he's not the one who went back in time, no problem.

In the self-consistent theory (there might be a better name, but I don't know it), any alterations you make in the past have already been made. They are part of the history that led up to your time travel in the first place. Paradoxes are impossible - the probability of such an event is zero, as it assumes multiple, inconsistent events occur.
One way to think of this is as similar to many-worlds, except with no branching - every world which is self-consistent exists, and every one with a paradox does not. While it appears to you you're going back in time to meet/kill/observe your mother, you're in fact just following a closed timelike curve through spacetime. The eventualities in which there is a paradox do not exist - even if you get to the past with killing intent, you will not be able to carry it out. Something will happen to prevent you carrying out your mission, from a simple attack of conscience to a sudden meteor strike.

Just kidding. I was just traveling back in time to say hi to gramps when I decided to see how the "old" internet was working. let me tell you about the future:
- still lots of spam
- geeks still not getting laid
- cmdrtaco promoted to admiral taco.

By necessity, since traveling backwards in time causes effects to occur before their cause. The universe stops making sense when causality is violated because causality is what makes the universe make sense in the first place.

Anyway, I think the authors may have seen this movie [imdb.com]. The idea is certainly not new.

This is pretty nifty. It reminds me of the old GURPS [wikipedia.org] time-travel rules supplement. Under those rules, time travel was possible, but it was not possible to change the past in a way inconsistent with your knowledge of the future -- the Game Master was instructed to thwart any such attempts by any means necessary, however unlikely. So, an organization of bad guys might try to take over ancient, remote civilizations where doing so would leave no evidence surviving into the present, while the good guys would go around recording as much information about history as possible in order to fix it in place, protecting it from the bad guys.

If you saw your buddy killed before your eyes, you would leave the scene immediately, and avoid examining the body in any way. Instead, you'd go get a dummy that looks like your buddy, then return to the time just before your buddy died, rescue him, and leave the dummy behind to "fool" your past self. I was delighted later on to see that in the game Chrono Trigger [wikipedia.org] it was possible to use exactly this mechanism to save the life of one of the characters in spite of their onscreen "death".

Something I don't think a lot of people really grok is that the laws of physics are time symmetric (actually the full symmetry is CPT, charge+parity+time, an electron going back in time would be a positron for example) so the fundamental weirdness is why we perceive time to flow in one direction in the first place. That's why I've always loved Feynman's absorber theory and it's associated spin-off the transactional interpretation of quantum mechanics. Those theories don't discard the so-called "advanced" (that is, backwards in time)solutions and work out how in a universe with appropriate boundary conditions you get an arrow of time. The advanced solutions actually exist but because of the boundary conditions they cancel each other out except where they "count".
So according to the theory, when you go to push an electron every other particle in the universe sends waves back in time in response to push back on the electron at the exact instant you push it! The advanced waves only manifest themselves as the normal radiation resistance we observe when accelerating charged particles. The transactional interpretation takes this line of thinking with regards to the collaspe of the wave function. When one particle of a two particle entangled system wave function collapses it sends an advance wave back in time to collapse the wave function of the other particle. So in the EPR experiment there is no instanteous "spooky action at a distance" but travel exactly at the speed of light but in the opposite direction in time.

The thing about time travel is that by nature, it has to be discovered simultaneously at all points in time. So, if we're not doing time travel right now, we never will. (At least random-access time travel. Someone might come up with a short term 'rewind' ala Superman or "Prince of Persia.")

The reason is...as soon as the first time machine is invented, then everyone from the future will jump back into the past and invent it first.

If we arbitrarly set time as a 4th dimension, which encompasses some arbitrary number of 3 dimensional states, space, then can't probability be a 5th dimension that contains all the different possible timelines?

We unintentionally move forward through the 4th dimension of time right now. Let's say we can move through time freely with a time machine, but by doing so there is an unintentional movement 5th dimensionally through possibility.

We see no time travelers because in our timeline the time machine is never created, but we might eventually create one, but every time we go back in time with it, we travel unintentionally through probability and there's probably already a bunch of time travellers there, we can't ever go back to our own original histories.

We, existing in this universe, are on a crash course toward the future.

There's no stopping it or slowing down of time, in the traditional sense. However, it might be possible (with the help of absolute zero) to stop all things in the area of the absolute zero. This would be akin to stopping time, as nothing could be happening within that area.

Unbaking a cake or uncracking an egg is a good example of going back in time. Hey, if you can take a fully-baked cake, reverse the steps, and make it back into cake-mix-egg-and-milk-inna-bowl, that's good enough time travel for me.

How can that even be remotely possible? Anything and EVERYTHING (no matter how small or big of an event it is) will change SOMETHING in the future.

Sci-fi writers have had two main theories for a long time. Either you can go back in time and change things, or you can go back in time and "fulfill" the past you expireinced. Just because you have an influence on the past doesn't mean your influence didn't shape time into the way you remembered it.

Anyone who thinks any differently needs to go back to school.

Yes, because I'm sure these quantum physicists haven't spent any time in school...

It's still hard to grok what this "prevention" means to the time traveller. If you go back, are you physically prevented from firing the gun or will the gun misfire? Or if you make a change, does the timeline establish a new universe with the old one running along merrily as a parallel universe.

When we use our senses, we only see things in the typical 4D realm, so is it possible that all those other postulated dimensions (to 11) give the degrees of freedom to allow bifurcations in the timeline? Geez this is confusing.

> If you go back, are you physically prevented from firing the gun or will the gun> misfire?

Something like that. Or you miss. Or you are killed in a traffic accident while crossing the street on your way to kill the guy.

Basically, anything you could do in the past, you have already done. History records that Hitler wasn't killed by a sniper--therefore events have already prevented you from going back in time and shooting him.

I don't like that. Let's say I travel back in time to two days before today and I land in wet cement, leaving foot prints. However, the day before I left (Which would be the day after I arrive), the cement layer came to work in the morning and saw no foot prints. Doesn't that prevent me from traveling back, because history records show the cement was smooth?

Or...Does it allow me to 'land' back in time *only* where my landing does not affect anything in the future. Where would that be? Wouldn't my biological struture have influence on just about any environment?

Doesn't work. At some point you would have had to decide to go to the past or not. What you are saying is that the past already contains whatever decision you made. If so that would mean you had no real choice. There has to be a beginning in order to have free will. If the past already contains all of our decisions of the present then we couldn't have really decided anything.

You are also thinking of the future as something undetermined but the past as determined and unchangable. Our present is the past of the future. For the past to be unchangable our present would also have to be unchangable. Again, we are back to no free will.

The whole point of time travel presenting us a paradox is because we think we have free will. If there is no possibility of a paradox then we have no free will.

Actually, philosophers have had the theories, but time-travel sci-fi is, like most sci-fi, just a futuristic take on one philosophical idea or another.

The "new" model is actually called the "B theory" of time and isn't new at all (although this scientific explanation of it is I guess). The B theory is that every instance in time exists somewhere and it is always "now" in that instance, so there is no real past, present or future. In the B theory if you were to go back in time you would merely fulfil the events that happen in that instance of time, always as the way they were intended.

So if you went back in an attempt to kill the parents of the bully who harassed you in school you would find out that your attempts failed, and that they didn't change your "present" at all. In fact, they would have helped created your present. A good example of this theory in effect is the sci-fi series "Andromeda", which follows the B theory of time in its time-travel episodes. A more well known example is the movie 12 Monkeys.

Star Trek on the other hand follows the multiple futures theory, whereby if you go back in time and change something you actually from that point on move down a different branch of time into an alternate future. The Butterfly Effect is another movie example of this.

The problem with the B theory of time is that it requires a deterministic universe, which is an unpleasant who isn't a materialist (ie. you believe you're made up of more than just matter). Of course the alternate timeline theory also has its own problems in that regard, wherein if you can exist in multiple timelines then which one is really you and where is your soul? If you're a materialist then no worries:p.

My own theory on the matter is that time is nothing more than a human construct. Matter changes, and one change takes place before another, and we measure the order in which these changes occur and call that 'time'.

I'm wondering if these changes to the future are limited to your observer's point of view. The future may well change, but only in ways that will not be observable to said observer. Then truth goes and gets even more relative.

It's the same question as asking if Schroedinger's cat notices if it is alive or dead. I assume it does, but that doesn't affect the outside observer.

What this sounds like to me: If you have directly or indirectly observed something occur, then there is no uncertaincy of it occuring. If you haven't directly seen something happen or been informed that it happened, then it may not have happened. Why do we need scientists to tell us this?

Because this is a horribly simplified and popularized version of actual scientific work. It happens all the time: you hear "Study says: People would be happier if they chose jobs they liked." Everyone posts to/. saying "I could have told you that, who's paying these guys?" And all it really is, is that there was actual good scientific research going on, and the press got ahold of the simplest sound bite they could and presented THAT. There's usually a lot more than meets the eye.

While trying to avoid sounding like a complete lunitic, I'll try to explain the best I can. I'm no expert in paranormal events, so some of my phrasing may be a bit off. I was corrected on my experience of "Deja Vu" a few months ago, being told it's really "Precognition".

I was told when I was a kid that if I live through an event a second time, where I'm sure it couldn't have happened before, it was a "Deja Vu". This was clarified by someone more into paranormal phenomena to be a precognition. A deja vu is where you've lived it once, and you're living it again, even though you probably weren't able to have lived it once before. Use the example from the Matrix, where he sees a black cat run by, and then turns to see the same black can run by the same way again.

My precognitions usually happen years before the real event. They come in dreams. Usually they're very clear events, as viewed from my own eyes. Hollywood never portrays them like that, usually to show the stars involved in the scenes.

The most notable one was a conversation I had with 4 complete strangers. I went to a city I hadn't been to before, with a new friend. We met 4 of his friends there, and through the evening, we were having a conversation. We ended up in a library, and for 10 seconds through the conversation, I knew exactly what everyone was to say. At the point where I was suppose to say something, I didn't say a word. By not saying my part, the next person to speak didn't say anything, because I had changed the chain of events. They continued talking, it was just that it changed subtly.

Another changed event was visiting a strange house as a child. We went to a house, and I asked to play downstairs. I named very specific details of the downstairs of the house, because I **KNEW** I had been there before. They corrected me in that I had never been there before, because they had just moved in, but my details of the basement were absolutely correct, including an item of furnature which was left there by the previous owner. I may have changed this event by mentioning it too early, or it may have been changed by someone else changing plans.

My precognitions come more frequently when "something" is going to happen. The precognitions never have anything to do with the event that is going to happen, they're just like warnings that it will happen. The event isn't necessarly important to me, about half the time they are. I may get precognitions several times a day when the event is coming close. After the event, they can completely go away for a while. Sometimes it's weeks, sometimes it's years.

I can usually remember when the dreams are from. Usually they don't make sense at all, because of the time that I have the vision. I pass them off as a weird dream, until it really happens.

For example, I was dating this really nice girl. I dated her for years. While I was dating her, I had this dream. I was with this other girl in my car. This was a nice car, which at the time I didn't have anything like. I was at a particular intersection in a city I had never been in. I was messing with the air conditioning controls, because this girlfriend had changed something while I was driving. She was also talking on a cell phone to my ex-girlfriend (the girl I was dating when I had the dream), and their conversation was exactly from the dream.

When I had the precognition, I didn't see the girlfriend in the dream, because I was looking out at the traffic, which was a very specific part of the precognition. I didn't know what she'd look like, and I didn't realize what it was until it all happened. That dream was about 4 years previous to the event.

I spoke with someone who does remote viewing professionally. He's described some of his work. One that he told me about was an event that he was asked to view where something important to the investigat